By virtue of small thickness, light weight and low power consumption, display devices, which are typified by liquid crystal display devices, have been used as displays of various kinds of apparatuses. Active matrix display devices, among others, have been gaining in popularity as displays of notebook-type personal computers and portable information terminals.
In the meantime, in the liquid crystal display device, if a voltage of a same polarity continues to be applied to a liquid crystal, a display defect occurs. Thus, polarity-inversion driving is adopted, in which a polarity of a voltage applied to the liquid crystal layer is switched at regular intervals. When the polarity-inversion driving is executed, it is necessary to cyclically change the polarity of the voltage of a power supply line. For this purpose, a plurality of reference power sources are prepared in advance.
However, at a time of power-on, it is uncertain to which of the reference power sources the power line is connected. As a result, the voltage applied to the liquid crystal layer varies, and there arises a problem that a display defect, such as flickering, is visually recognized. To cope with this problem, there has been proposed a display device which is configured such that no display defect is visually recognized at a time of power-on.
In the proposed invention, however, the power supply voltage is applied to all pixels at a time of power-on. Thus, when this invention is applied hereafter to a display device, such as FHD (full high-vision), which has a higher resolution than a conventional display device, an instantaneous current due to switching of the power supply voltage increases, and, consequently, a load on a driving circuit increases, leading to a cause of the occurrence of a fault of the display device. In addition, due to the increase in electric current, there is concern that the specifications, which are required for the display device, are judged to be unachieved.